Artificial lawn with hollow grass blades

ABSTRACT

An artificial lawn able to absorb and store quantities of water. The stored water is released only when the lawn is walked upon and is available to improve its sliding properties. The artificial lawn includes blades which are at least partly hollow and can consist of small U-shaped tubes. The small tubes can further have openings in their lateral wall so as possibly to be able to absorb water also from the support layer or from a water-storing layer.

DESCRIPTION

The invention relates to an artificial lawn with at least partly hollowplastic blades, which are attached to a support layer.

Artificial lawns are provided with blades, consisting of filaments ofdifferent thickness and length, which are attached to a support layer.In most cases the support layer is a plastic wire netting in which thewire filaments are embedded. Normally the wire filaments are processedby means of tufting, knitting or another mechanical method, so that agrass turf is created. The material of the blades is mostlypolypropylene (PP), polyamide (PA), polystyrene (PS) or Polyethylene(PE), whereby these plastics are coloured green or the like. The wire orgrass filaments can also be bundled into a bundle and as such fastenedin the support layer. The structure of the blades can be smooth, curledor corrugated, making it suitable for each application. The grassfilaments can have different lengths and can be adapted to theapplication.

Artificial lawns have to be moistened, like natural grass, in order toavoid static charges and excessive heat and also to acquire improvedsliding characteristics, thereby reducing the risk of injuries due to asliding. Moistening results in an improved mini-climate. Moistening canbe done using an overground irrigation system or a subterraneanirrigation system. Since the storing capacity of the artificial lawns ismainly determined by the affixture of water to the blades and that theaffixed water will quickly evaporate due to solar radiation, the waterconsumption will be very high by warm weather conditions and amounts toabout 10 m³ per 6000 m² artificial lawn surface. 30% to 50% of thatamount leaks unused into the ground. Wind and maintenance activitiesalso reduce the amount of affixed water, resulting in a shortage at thetime of playing. At higher temperatures moistening has to be performedseveral times per day.

U.S. Pat. No. 5,601,886 discloses an artificial lawn with blades havingcurled, or spiral shaped wounded filaments respectively. The waterstoring capacity is small, due to the partly high density of thewindings, and the eventually stored water can leak freely in downwarddirection. Such blades are unsuitable for storing water.

In an WDE-41 36 341 A1 filament shaped plastic blades are known, whichare implanted on a water-storing layer. However the blades themselvesare uncapable of storing moisture.

It is an object of the invention to provide an artificial lawn, which iscapable of absorbing and storing more water, whereby said stored watercan be released only when treaded, thereby improving the slidingcharacteristics.

This object is obtained by an artificial lawn, whereby said blades areconstructed as small tubes.

The blades are capable of storing water from rain, mist, air humidityand moistening devices using capillary forces.

Water stored in said blades is protected against solar radiation andwind and will only be released, wenn the blades are squeezed due towalking. Hollow blades have the advantage, that they can store a muchgreater amount of water and that water can be released at the time it isrequired.

Advantageously said hollow tubes have a U-shape and are attached to thesupport wire netting by means of tufting or knitting, whereby the openlegs of the -U- are pointing upwards for storing water.

Usually the ordinary grass-filaments are bundled into a bundle ofblades. This method is also applicable to blade tubes, whereby theU-shaped tubes are attached to the wire netting. This means, that airpresent in each leg of the U-shaped tubes can not escape, when water isentering, thereby hindering the absorbing of water under certaincircumstances. It is therefore prefered to provide at least one ventopening in the wall of the tube, perferably directly above the supportlayer. The opening or openings in the wall of the blades are preferablyso small, that the stored water is prevented from leaking through theopenings.

The U-shaped tubes can also be attached to the support wire netting,whilst not being pinched off. The U-shaped tubes are then with theirlower side glued to the support layer using suitable plastics.

When furthermore, the support layer is provided with a water-storinglayer consisting of a membrane or a foam, the openings can be partly orsolely located near the support layer or the water-storing layer. Thehollow blade is then also capable of absorbing moisture out of thesupport layer using capillary forces. This is very advantageous in theevent that during playing nearly all the water has been squeezed offfrom the blades, but that there is still some water present in thestoring layer. A refilling of the hollow blades can thus take placeduring playing.

In order to fascilitate the filling of the hollow blades by means ofcapillary forces a hydrophilic material is preferably used formanufacturing the tubes. A further possibility is the application of ahydrophilic layer to the interior wall of the tubes.

For example the tubes can be manufactured using an extrusion technique.

Specific embodiments of the invention are described below in view of thedrawings.

They show in:

FIG. 1 a side view and partly a sectional view of a schematic embodimentof a part of an artificial lawn with blades;

FIG. 2 a side view of a bundle of blades according to anotherembodiment; and

FIG. 3 a side view of a bundle of blades according to a furtherembodiment.

FIG. 1 discloses a support layer 2 with attached blades 4. The bladesare U-shaped tubes 7, having the legs of the tubes 7 in uprightposition, wherein the openings 8 a, 8 b are pointing upwards allowingthe entry of raining water and the storage inside the tubes. The storedwater 10 can fill the tubes completely.

FIG. 2 shows a further embodiment, wherein the blades 4 and the tubes 7respectively are combined as a bundle of blades 5. Said bundles areprepared in advance, whereby the tubes in the middle of area 6 arebundled together. The tubes 7 can be pinched off at that position undercertain circumstances (not disclosed in FIG. 2), preventing thetransport of fluid. This prevents a further entry of water, inparticulary when, seen from the connection 6, the tube is filled withair. As a remedy, in order to support the entry of water, when—as shownin FIG. 2—the tubes of the bundle are not pinched off, at least oneopening 9 is present, which is located directly above the upper surfaceof the support layer 2. Air can escape through this opening upon theentry of water through the openings 8 a and 8 b. The section of theopenings 9 is so small, that water already entered can not flow away.

FIG. 3 depicts a support layer 2 furthermore provided with awater-storing layer 3. A bundle 5 of blades is attached to this layer,thereby positioning the opening 11 near the support layer 2 and/or thewater-storing layer 3. With this embodiment the tubes 7 are capable ofabsorbing fluid from the water-storing layer 3 via said openings 11.

What is claimed is:
 1. Artificial lawn comprising: at least partlyhollow plastic blades attached to a support layer, said blades beingtubes and being U-shaped.
 2. Artificial lawn according to claim 1,wherein said tubes are made from a hydrophilic material.
 3. Artificiallawn according to claim 1, wherein said tubes are provided on aninterior wall with a hydrophilic layer.
 4. Artificial lawn comprising:at least partly hollow plastic blades attached to a support layer, saidblades being tubes provided in a lateral wall with at least one opening.5. Artificial lawn according to claim 4, further comprising awater-storing layer, said at least one opening is located within atleast one of said support layer and said water-storing layer. 6.Artificial lawn according to claim 4, wherein said tubes are made from ahydrophilic material.
 7. Artificial lawn according to claim 4, whereinsaid tubes are provided on an interior wall with a hydrophilic layer.